In the course of practicing the invention disclosed in U.S. Pat. No. 4,629,319, which is herein incorporated by reference, we have found certain liabilities to the embodiments of FIGS. 6, 7, and 8a thereof (wherein an area of, in general, a substantial portion of an object is illuminated). These liabilities limit the total area of the surfaces which can be imaged and complicate the detection and analysis of defects. They are unavoidable by-products of the optical apparatus configuration disclosed in the referenced invention.